int sf(char *s1, char *s2)
{ while(*s1==*s2){
  if(*s1==0)return 0;/*比较两个字符数组的大小*/
s1++;,
s2++;   }
return (*s-*t);
#include<stdio.h>
int main()
int sf(char *s1,char *s2);
char *s1,*s2;
scanf("%s\n%s",s1,s2);
sf(s1,s2);
}